Highly refractive thin glasses

Abstract

Glass sheets with high refractive indexes (nd), layer composite assemblies including the glass sheets, methods for manufacturing the glass sheets, and methods of using the glass sheets are all provided. The glass sheets can be processed in a glass sheet manufacturing process and nevertheless have the optical properties of a classical optical glass. The glass sheets of the are highly transparent, resistant to crystallization, chemically resistant and highly refractive. The glass sheets have a viscosity-temperature behavior that is adapted to the manufacturing procedure with glass sheet manufacturing processes.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation-in-part of U.S. application Ser. No. 13 / 882,011 filed on Jul. 12, 2013, which is a National Stage of International Application No. PCT / EP2011 / 068637 filed on Oct. 25, 2011, which claims the benefit of German Application No. 10 2010 042 945.7 filed on Oct. 26, 2010, and this Application claims the benefit of German Application No. 10 2014 109 831.5 filed on Jul. 14, 2014, the contents of all of which are incorporated by reference herein.BACKGROUND[0002]1. Field of the Invention[0003]This invention relates to thin glasses having a high refractive index (nd), a layer composite comprising these thin glasses, a method for the production of the thin glasses and their uses.[0004]2. Description of Related Art[0005]Glasses having refractive indexes in the range of above nd=1.5 up to nd=1.7 are well known. In the field of technical glasses, however, they are achieved by the addition of high amounts of lead oxide w...

AI Technical Summary

Benefits of technology

The patent aims to create a thin glass that can be processed using flat glass manufacturing methods and also has the optical properties of conventional optical glass. The glass is highly transparent, resistant to crystallization, chemically resistant, and has high refractive power. Its viscosity-temperature behavior is adapted to the production process with flat glass manufacturing methods. Overall, the technical effect of this patent is to create a thin glass that combines the processability of technical glass with the optical properties of optical glass.

Problems solved by technology

In the field of technical glasses, however, they are achieved by the addition of high amounts of lead oxide which is questionable from an ecological point of view and also disadvantageous for large economic processes.

Generally, glasses having refractive indexes of >1.6 are hardly suitable for technical hot forming methods, since most often they have a “steep” viscosity curve (strong change of viscosity with temperature, i.e. “short” glass properties) and most often a high tendency to crystallization.

In the case of technical hot forming methods, compared to the production of ingots, these properties are a problem, since the residence time in the large technical aggregates is considerably longer and thus also the pre-nucleation / nucleation time.

Furthermore, there are significantly longer residence times of the materials in the aggregates due to the flow conditions and the size of the aggregates.

This indeed results in longer glasses with reduced tendency to crystallization, but also in a considerable loss of refractive index and dispersion properties.

Thus, for example, standard optical components, such as the oxides of lead, bismuth, tungsten as well as the conventional polyvalent refining agents (arsenic), the effective action of which is exactly based on the shift of the redox equilibrium, cannot be used.

But it is obvious that the cutting and polishing steps of such ingot sections are extremely expensive, and in addition they stress the glass very strongly.

Thus, in this manner very small thicknesses together with large dimensions cannot be achieved.

When thin glasses are mechanically polished, then this results in surface conditions which are not optimal.